Due to the different material properties, differences in the manufacturing process, as well as bearing capacity of plastic gear design also differs from the metal gear.

    In addition to considering the impact strength, tensile strength and substandard cost must also be considered when material selection hygroscopic material such as plastic gears.

    Two plastic gears currently used materials are nylon and acetal, both chemical resistance, can be used as a lubricant oil or grease; it is usually caused by the use of two materials of gears gears, because it than the single species composition of the material gear gears friction coefficient is small, basically do not need additional lubrication. If a material need to add a small amount of oil or grease lubricated. Design gear design plastic gears and metal gears basically the same, but the tooth root fillet should be a smooth curve formation.
 
    Another difference between the metal gear and plastic gear teeth into engagement are different ways. Under heavy load, the more plastic gears metal gears bent badly, this time into the heart of meshing teeth become different, and embedded in the top of each other.
 
    Mold design gear needs special attention, in a standard gear reducer box, there is a group of different sized gears, in order to reduce manufacturing costs, the designer may create all the gears in a mold, the mold that is family gear. When applied to the gear with a small gap, it is not suitable for the family mold gears manufactured.